With the continuous progress of the network technology, the demands of communication bandwidth also increase continuously. Meanwhile, various transmission media are also developed subsequently, such as microwave communication, satellite communication, etc. Among those transmission media, fiber optic communication plays an increasingly important role.
In the past, signals in the fiber optic communication are generally transmitted in a continuous mode. The so-called continuous mode means that the design of fiber optic signal avoids using too many identical bits, thereby preventing a phase-latch loop from losing the signal-latching function. In other words, since no interruption occurs in the process of signal transmission, the structure of the fiber optic communication can merely be set up as one receiver to one sender, which is also called as a P2P (Point to Point) structure.
As to the optical fiber used as the communication backbone, since the quantity of data transmission is quite huge, such as 2.5 Gbit/sec, 10 Gbit/sec or more, these is no big problem to apply the P2P structure therein. However, for applying FTTX (Fiber To The X, wherein X stands for residence, buildings, etc.) to the aforementioned fiber optic communication, since the signal demands are not continuous with interruption, the P2P structure will result in a lot of waste of bandwidth for daily applications.
To tackle with the aforementioned problem, some fiber optic communication developers present a FSAN (Full Service Access Network) structure for use in FTTX applications. In FSAN, there is an important concept called P2 MP (Point To Many Points, i.e. one point to multiple points). Speaking plainly, in P2 MP, a center office is used to transmit information to a plurality of clients, and those clients also can transmit information to the center office. A TDM (Time Division Multiplexer) can be used in the paths between the clients and the center office, and the so-called TDM means assigning a time slot to each of clients. Once the clients have information to be transmitted, the clients can transmit the information immediately, and can shut down the laser beam immediately after the information has been transmitted, thereby avoid signal collisions. The aforementioned transmission method is also called a burst mode, which is different from the aforementioned continuous mode.
As to the burst-mode fiber optic communication, its main duty resides in a laser driven integrated chip. Since input communication signals appear very shortly in the burst-mode transmission, the laser driven integrated chip has to rely on the short communication signals to drive a communication laser diode, and shut off the laser power completely when no communication signal is inputted.
Under the FSAN standard, there is no clear definition with respect to the present and stop time, so that system integrators adopt various design methods, and some of them need to use very strict time controls, therefore making the laser driven integrated chip more difficult to be assembled, thus increasing the fabrication cost.
Presently, most of the laser driven integrated chips suitable for continuous mode existing in the market, but very few of them are particularly design for the burst mode application. For this reason, the laser driven integrated chips of particularly design for the burst mode application are very expensive. If some special chips are redesigned and redeveloped for the burst mode, not only the existing design results are totally wasted, but also the expansion of the optical communication field is blocked. Hence, how to search for a cost-effective design method of a laser driven integrated chip has become a very important issue.